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Unformatted text preview: the assumption that the data being read or written are held in cache. As Figure 5.12 shows, both of these units have a latency of 3, and an issue time of 1. All of our programs so far have used only load operations, and they have had the property that the address of one load depended on incrementing some register, rather than as the result of another load. Thus, as shown in Figures 5.15 to 5.18, 5.21 and 5.26, the load operations could take advantage of pipelining to initiate new load operations on every cycle. The relatively long latency of the load operation has not had any adverse affect on program performance. 5.13.1 Load Latency
As an example of code whose performance is constrained by the latency of the load operation, consider the function list_len, shown in Figure 5.30. This function computes the length of a linked list. In the loop of this function, each successive value of variable ls depends on the value read by the pointer reference ls->next. Our measurements show that function list_len has a CPE of 3.00, which we claim is a direct reﬂection of the latency of the lo...
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- Spring '10
- The American